读取并分析wgetrc文件

main():

  /* If the user did not specify a config, read the system wgetrc and ~/.wgetrc. */
  if (use_userconfig == false)
    initialize ();

initialize():

/* Initialize the defaults and run the system wgetrc and user's own
   wgetrc.  */
void
initialize (void)
{
  char *file, *env_sysrc;
  bool ok = true;


  /* Run a non-standard system rc file when the according environment
     variable has been set. For internal testing purposes only!  */
  env_sysrc = getenv ("SYSTEM_WGETRC");
  if (env_sysrc && file_exists_p (env_sysrc))
    {
      ok &= run_wgetrc (env_sysrc);
      /* If there are any problems parsing the system wgetrc file, tell
         the user and exit */
      if (! ok)
        {
          fprintf (stderr, _("\
Parsing system wgetrc file (env SYSTEM_WGETRC) failed.  Please check\n\
'%s',\n\
or specify a different file using --config.\n"), env_sysrc);
          exit (2);
        }
    }
  /* Otherwise, if SYSTEM_WGETRC is defined, use it.  */
#ifdef SYSTEM_WGETRC
  else if (file_exists_p (SYSTEM_WGETRC))
    ok &= run_wgetrc (SYSTEM_WGETRC);
  /* If there are any problems parsing the system wgetrc file, tell
     the user and exit */
  if (! ok)
    {
      fprintf (stderr, _("\
Parsing system wgetrc file failed.  Please check\n\
'%s',\n\
or specify a different file using --config.\n"), SYSTEM_WGETRC);
      exit (2);
    }
#endif
  /* Override it with your own, if one exists.  */
  file = wgetrc_file_name ();
  if (!file)
    return;
  /* #### We should canonicalize `file' and SYSTEM_WGETRC with
     something like realpath() before comparing them with `strcmp'  */
#ifdef SYSTEM_WGETRC
  if (!strcmp (file, SYSTEM_WGETRC))
    {
      fprintf (stderr, _("\
%s: Warning: Both system and user wgetrc point to %s.\n"),
               exec_name, quote (file));
    }
  else
#endif
    ok &= run_wgetrc (file);


  /* If there were errors processing either `.wgetrc', abort. */
  if (!ok)
    exit (2);


  xfree (file);
  return;
}

run_wgetrc():

/* Initialize variables from a wgetrc file.  Returns zero (failure) if
   there were errors in the file.  */

bool
run_wgetrc (const char *file)
{
  FILE *fp;
  char *line;
  int ln;
  int errcnt = 0;

  fp = fopen (file, "r");
  if (!fp)
    {
      fprintf (stderr, _("%s: Cannot read %s (%s).\n"), exec_name,
               file, strerror (errno));
      return true;                      /* not a fatal error */
    }
  ln = 1;
  while ((line = read_whole_line (fp)) != NULL)
    {
      char *com = NULL, *val = NULL;
      int comind;

      /* Parse the line.  */
      switch (parse_line (line, &com, &val, &comind))
        {
        case line_ok:
          /* If everything is OK, set the value.  */
          if (!setval_internal_tilde (comind, com, val))
            {
              fprintf (stderr, _("%s: Error in %s at line %d.\n"),
                       exec_name, file, ln);
              ++errcnt;
            }
          break;
        case line_syntax_error:
          fprintf (stderr, _("%s: Syntax error in %s at line %d.\n"),
                   exec_name, file, ln);
          ++errcnt;
          break;
        case line_unknown_command:
          fprintf (stderr, _("%s: Unknown command %s in %s at line %d.\n"),
                   exec_name, quote (com), file, ln);
          ++errcnt;
          break;
        case line_empty:
          break;
        default:
          abort ();
        }
      xfree_null (com);
      xfree_null (val);
      xfree (line);
      ++ln;
    }
  fclose (fp);

  return errcnt == 0;
}

parse_line():

static enum parse_line
parse_line (const char *line, char **com, char **val, int *comind)
{
  const char *p;
  const char *end = line + strlen (line);
  const char *cmdstart, *cmdend;
  const char *valstart, *valend;

  char *cmdcopy;
  int ind;

  /* Skip leading and trailing whitespace.  */
  while (*line && c_isspace (*line))
    ++line;
  while (end > line && c_isspace (end[-1]))
    --end;

  /* Skip empty lines and comments.  */
  if (!*line || *line == '#')
    return line_empty;

  p = line;

  cmdstart = p;
  while (p < end && (c_isalnum (*p) || *p == '_' || *p == '-'))
    ++p;
  cmdend = p;

  /* Skip '=', as well as any space before or after it. */
  while (p < end && c_isspace (*p))
    ++p;
  if (p == end || *p != '=')
    return line_syntax_error;
  ++p;
  while (p < end && c_isspace (*p))
    ++p;

  valstart = p;
  valend   = end;

  /* The syntax is valid (even though the command might not be).  Fill
     in the command name and value.  */
  *com = strdupdelim (cmdstart, cmdend);
  *val = strdupdelim (valstart, valend);

  /* The line now known to be syntactically correct.  Check whether
     the command is valid.  */
  BOUNDED_TO_ALLOCA (cmdstart, cmdend, cmdcopy);
  dehyphen (cmdcopy);
  ind = command_by_name (cmdcopy);
  if (ind == -1)
    return line_unknown_command;

  /* Report success to the caller. */
  *comind = ind;
  return line_ok;
}